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作 者:韩斐斐[1] 姜立春[1] Han Feifei Jiang Li- chun(Northeast Forestry University, Harbin 150040, P. R. China)
机构地区:[1]东北林业大学,哈尔滨150040
出 处:《东北林业大学学报》2017年第4期65-69,共5页Journal of Northeast Forestry University
基 金:"十二五"国家科技支撑计划项目(2012BAD22B0202);国家自然科学基金项目(31570624)
摘 要:以大兴安岭兴安落叶松为研究对象,基于树干15个不同相对高度处直径和1.3 m处胸径分别建立一元和二元材积方程。利用S-PLUS软件的广义非线性GNLS模块对各模型进行拟合。采用指数函数、幂函数和常数加幂函数对立木材积模型拟合过程中产生的异方差现象进行校正。采用确定系数(R2)、均方根误差(ERMS)、平均误差绝对值(B_(MA))和相对误差绝对值(B_(MP))4个指标对模型进行评价。结果表明,基于树干相对高度30%处直径的一元和二元模型拟合效果最好。模型检验结果表明:相对于传统的一元模型,基于相对树高30%处直径的一元模型的ERMS、B_(MA)和B_(MP)分别降低了25.6%、24.7%、24.7%;相对于传统的二元模型,基于相对树高30%处直径的二元模型的ERMS、B_(MA)和B_(MP)分别降低了55.6%、41.2%、41.2%。二元模型的检验精度明显优于相应的一元模型。One-variable and two-variable volume equations were established based on 15 sets of diameters at different relative height and diameter at breast height(1.3 m)for Larix gmelinii in Daxinganling.All models were fitted using GNLS in S-PLUS.Variance functions(exponential function,power function and constant plus power function)were incorporated into generalized models to reduce heteroscedasticity.Coefficient determination(R2),root mean square error(ERMS),mean absolute bias(B_(MA)),and mean percentage of bias(B_(MP))were employed to evaluate the precision of different individual volume models.The best one variable and two variable volume equations were found based on the diameter of thirty percent of relative height.By model validation,one variable model based on diameter at 30%relative height reduced ERMS,B_(MA) and B_(MP)by 25.6%,24.7%,and 24.7%,respectively,in comparison with traditional one-variable model.Compared with traditional two-variable model,the model based on diameter at 30%relative height reduced ERMS、B_(MA)and B_(MP)by 55.6%,41.2%,and 41.2%,respectively.Prediction precision of two-variable model is better than that of one-variable model.
关 键 词:兴安落叶松 相对高度直径 异方差 材积 预测精度
分 类 号:S758.1[农业科学—森林经理学]
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